Using head and/or drive performance information for predicting and/or ascertaining failures

ABSTRACT

A computer-implemented method, according to one embodiment, includes: collecting performance data corresponding to a tape drive and/or a magnetic tape head, storing the performance data in memory, and using the data to perform problem analysis. The performance data includes a resistance of the tape drive and/or magnetic tape head and a resolution of the tape drive and/or the magnetic tape head. Moreover, performing the problem analysis includes: determining a condition of the tape drive and/or the magnetic tape head, wherein the condition is selected from a group consisting of: wear, corrosion, defective leads and wire bonds. Other systems, methods, and computer program products are described in additional embodiments.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to using performance data from tapeheads and/or tape drives to predict future failure conditions.

In magnetic storage systems, magnetic transducers read data from andwrite data onto magnetic recording media. Data is written on themagnetic recording media by moving a magnetic recording transducer(Writer) to a position over the media where the data is to be stored.The Writer then generates a magnetic field, which encodes the data intothe magnetic media. Data is read from the media by similarly positioningthe magnetic read transducer (Reader) and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, the drive moves the magnetic tape over thesurface of the tape head at high speed. Usually the tape head isdesigned to minimize the spacing between the head and the tape. Thespacing between the magnetic head and the magnetic tape is crucial andso goals in these systems are to have the recording gaps of thetransducers, which are the source of the magnetic recording flux in nearcontact with the tape to effect writing sharp transitions, and to havethe read elements in near contact with the tape to provide effectivecoupling of the magnetic field from the tape to the read elements.

BRIEF SUMMARY

A computer-implemented method, according to one embodiment, includes:collecting performance data corresponding to a tape drive and/or amagnetic tape head, storing the performance data in memory, and usingthe data to perform problem analysis. The performance data includes aresistance of the tape drive and/or magnetic tape head and a resolutionof the tape drive and/or the magnetic tape head. Moreover, performingthe problem analysis includes: determining a condition of the tape driveand/or the magnetic tape head, wherein the condition is selected from agroup consisting of: wear, corrosion, defective leads and wire bonds.

A computer program product, according to another embodiment, includes acomputer readable storage medium having program instructions embodiedtherewith, the program instructions executable by a controller to causethe controller to: collect, by the controller, performance datacorresponding to a tape drive and/or a magnetic tape head, store, by thecontroller, the performance data in memory, and use, by the controller,the data to perform problem analysis. The performance data includes aresistance of the tape drive and/or magnetic tape head and a resolutionof the tape drive and/or the magnetic tape head. Moreover, performingthe problem analysis includes: determining, by the controller, a causeof an issue of the tape drive and/or the magnetic tape head, wherein thecause of the issue is selected from a group consisting of: wear,corrosion, defective leads and wire bonds.

A system, according to yet another embodiment, includes: a processor andlogic integrated with and/or executable by the processor, the logicbeing configured to cause the processor to: collect performance datacorresponding to a tape drive and/or a magnetic tape head, store theperformance data in memory, and use the data to perform problemanalysis. The performance data includes a resistance of the tape driveand/or magnetic tape head and a resolution of the tape drive and/or themagnetic tape head. Moreover, performing the problem analysis includes:determining a condition of the tape drive and/or the magnetic tape head,wherein the condition is selected from a group consisting of: wear,corrosion, defective leads and wire bonds.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2A illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2B is a tape bearing surface view taken from Line 2B of FIG. 2A.

FIG. 2C is a detailed view taken from Circle 2C of FIG. 2B.

FIG. 2D is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIG. 8A is a flowchart of a method according to one embodiment.

FIG. 8B is a flowchart of sub-operations of the method in FIG. 8Aaccording to one embodiment.

FIG. 9 is a normalized amplitude vs. bit error rate vs. time graphaccording to one embodiment.

FIG. 10A is a flowchart of a method according to one embodiment.

FIG. 10B is a flowchart of sub-operations of the method in FIG. 10Aaccording to one embodiment.

FIGS. 11A-11B are graphs showing change in resistance vs. elapsed timefor performance information of a tape drive according to two differentembodiments.

FIGS. 12A-12B are graphs showing change in signal to noise ratio (SNR)vs. elapsed time for performance information of a tape drive accordingto two different embodiments.

FIGS. 13A-13B are graphs showing change in C1 bit error rate (BER)measurements vs. elapsed time for performance information of a tapedrive according to two different embodiments.

FIGS. 14A-14B are graphs showing change in C1 BER measurements vs.elapsed time for performance information of a tape drive according totwo different embodiments.

FIGS. 15A-15B are graphs showing change in C2 BER measurements vs.elapsed time for performance information of a tape drive according totwo different embodiments.

FIGS. 16A-16B are graphs showing change in C2 BER measurements vs.elapsed time for performance information of a tape drive according totwo different embodiments.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems, as well as operation and/or component partsthereof.

In one general embodiment, a computer-implemented method includescollecting, by the computer, performance data corresponding to a tapedrive and/or a magnetic tape head. The performance data is stored inmemory, and used by the computer to perform problem analysis. Theperformance data may include data such as one or more of a currentand/or a voltage applied to one or more transducers in the magnetic tapehead, a signal to noise ratio, a bit error rate, a resistance of a readsensor in the magnetic tape head, a read-back amplitude of the readsensor, asymmetry of the read-back amplitude, resolution, spacing loss,whether a magnetic orientation of a magnetic layer is reversed for oneor more of the transducers whether a short has occurred.

In another general embodiment, a computer-implemented method includescollecting, by the computer, performance data corresponding to a tapedrive and/or a magnetic tape head. The collected performance data iscondensed to reduce a size of the collected performance data. Thecondensed performance data is stored in memory, and used to performproblem analysis.

In yet another general embodiment, a computer-implemented methodincludes collecting, by the computer, performance data corresponding toa tape drive and/or a magnetic tape head. The performance data is storedin memory, and used by the computer to perform problem analysis.Performing the problem analysis includes predicting future failureconditions of the tape drive and/or the magnetic tape head.

In one general embodiment, a computer program product includes acomputer readable storage medium having program instructions embodiedtherewith, the program instructions readable and/or executable by acontroller to cause the controller to collect, by the controller,performance data corresponding to a tape drive and/or a magnetic tapehead. The performance data is stored in memory, and used to performproblem analysis. Performing the problem analysis includes trackingchanges to the performance data over time, and extrapolating futurefailure conditions of the tape drive and/or the magnetic tape head fromthe tracked changes in the performance data.

In another general embodiment, a system includes a processor and logicintegrated with and/or executable by the processor, the logic beingconfigured to cause the processor to collect performance datacorresponding to a tape drive and/or a magnetic tape head, where theperformance data includes a resistance of the tape drive and/or magnetictape head and a resolution of the tape drive and/or the magnetic tapehead. The logic is also configured to cause the processor to store theperformance data in memory, and use the data to perform problemanalysis. Performing the problem analysis includes determining at leastone of wear, corrosion, and defective leads or wire bonds of the tapedrive and/or the magnetic tape head.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the drive 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both. Servotransducers are also used to locate the read/write transducers on theappropriate tracks. Since servo transducers are similar to data readers,just with different geometries, for the purpose of this disclosure, aread element may also refer to a servo read element.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may operate under logicknown in the art, as well as any logic disclosed herein. The controller128 may be coupled to a memory 136 of any known type, which may storeinstructions executable by the controller 128. Moreover, the controller128 may be configured and/or programmable to perform or control some orall of the methodology presented herein. Thus, the controller may beconsidered configured to perform various operations by way of logicprogrammed into a chip; software, firmware, or other instructions beingavailable to a processor; etc. and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (integral or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some embodiments, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreembodiments, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, read-only memory (ROM) device, etc., embedded intoor coupled to the inside or outside of the tape cartridge 150. Thenonvolatile memory is accessible by the tape drive and the tapeoperating software (the driver software), and/or other device.

By way of example, FIG. 2A illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 3 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B made of the same orsimilar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2B illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2B of FIG. 2A. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 22 data bands, e.g., with 16data bands and 17 servo tracks 210, as shown in FIG. 2B on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2C depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2B of FIG. 2B. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2C, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2 and 2A-B together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2D shows a partial tape bearing surface view of complimentarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write transducer 214 and the readers, exemplified by the readtransducer 216, are aligned parallel to an intended direction of travelof a tape medium thereacross to form an R/W pair, exemplified by the R/Wpair 222. Note that the intended direction of tape travel is sometimesreferred to herein as the direction of tape travel, and such terms maybe used interchangeable. Such direction of tape travel may be inferredfrom the design of the system, e.g., by examining the guides; observingthe actual direction of tape travel relative to the reference point;etc. Moreover, in a system operable for bi-direction reading and/orwriting, the direction of tape travel in both directions is typicallyparallel and thus both directions may be considered equivalent to eachother.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked magnetoresistive (MR) headassembly 200 includes two thin-film modules 224 and 226 of generallyidentical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AlTiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe (−), CZTor Al—Fe—Si (Sendust), a sensor 234 for sensing a data track on amagnetic medium, a second shield 238 typically of a nickel-iron alloy(e.g., ˜80/20 at % NiFe, also known as permalloy), first and secondwriter pole tips 228, 230, and a coil (not shown). The sensor may be ofany known type, including those based on MR, GMR, AMR, TMR, etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further embodiments, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α₂ of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the skiving edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle α2 over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,read and/or write elements 322 may be located near the trailing edges ofthe outer modules 302, 306. These embodiments are particularly adaptedfor write-read-write applications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle α2 is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α2 is approximately tan⁻¹(δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.3° to about 1.1°, though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle α₃ on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller α₃tends to oppose what has heretofore been a steeper exiting effectivewrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno data readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thespacing between the substrate and closure (SC-span), the SC-span lengthcan be substantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical SC-spanis 20-35 microns. However, irregularities on the tape may tend to droopinto the SC-span and create SC-span erosion. Thus, the smaller theSC-span is the better. The smaller SC-span enabled herein exhibits fewerwear related problems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used linear tape open (LTO) tape head spacing. The openspace between the modules 302, 304, 306 can still be set toapproximately 0.5 to 0.6 mm, which in some embodiments is ideal forstabilizing tape motion over the second module 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an embodimentwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

FIG. 7 illustrates an embodiment where the modules 302, 304, 306 are inan overwrap configuration. Particularly, the tape bearing surfaces 308,312 of the outer modules 302, 306 are angled slightly more than the tape315 when set at the desired wrap angle α₂ relative to the second module304. In this embodiment, the tape does not pop off of the trailingmodule, allowing it to be used for writing or reading. Accordingly, theleading and middle modules can both perform reading and/or writingfunctions while the trailing module can read any just-written data.Thus, these embodiments are preferred for write-read-write,read-write-read, and write-write-read applications. In the latterembodiments, closures should be wider than the tape canopies forensuring read capability. The wider closures may require a widergap-to-gap separation. Therefore a preferred embodiment has awrite-read-write configuration, which may use shortened closures thatthus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother embodiments, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads.

The performance of the Read/Write heads can degrade over time. Thedegradation is often gradual, but may not be evident in the written datacapacity. For a degrading tape head, at some level of Read/Write errors,the drive will fail. Sudden failure can be disruptive to the user of thetape drive. A means of predicting when the failure occurred can allowthe operator to replace the degrading head in a controlled manner,avoiding data loss and/or extra recovery time.

Tape drives are used in a wide number of embodiments to store largeamounts of data. Thus, if a tape drive fails suddenly, a significantamount of time and effort is consumed to rapidly replace the faileddrive in addition to determining how much of the data which was in theprocess of being written to tape when the drive failed should bere-written on the same, or a different tape, e.g., due to write errorscaused by the failed tape drive.

When a failure occurs, the history of the tape drive's performance andthe corresponding functional parameters may be used to determine thecause of the tape drive failure. In some embodiments, the performanceinformation and functional parameters associated with a given tape driveand/or a magnetic head thereof may be used to improve failure analysiswhich may assist in avoiding future problems. However, internal memoryfor tape drives is limited and therefore the amount of information whichmay be stored for a given tape drive may be limited as well.

Some tape drives collect and store drive information in a file called a“dump” which contains a relatively large amount of data. In view of thelimited amount of internal storage space in a tape drive, a limitednumber of dump files may be maintained in a given tape drive. Accordingto an example which is in no way intended to limit the invention, a dumpfile may be collected and stored when the tape drive is first builtDump_(timeIntial), and a second dump file may be collected and storedwhich gives the final state of the tape drive Dump_(timeFinal). However,Dump_(timeFinal) cannot be retrieved if the corresponding tape drive hasexperienced a failure, and reconstructing the large amount of dataincluded in a dump file is difficult.

Furthermore, dump files are often not structured and thus the time toextract a given data parameter is slow, and often the relevantparameters may not even have been stored at the same time/use timepoint. Because of the above mentioned limitations, reconstructing when afailure occurred and posting a warning to the drive operator prior to afailure is too slow to be practical and reconstructing the cause of thefailure and when it occurred is difficult, if not impossible.

Furthermore, some failure conditions, such as corrosion of the readelements included in a tape drive, may be initiated at a point in timealthough the drive continues to operate. Thus, even after the drivefinally fails and is replaced, the corrosive agent may still linger andtake hold in the replacement drive, thereby causing the replacementdrive to fail as well. In some embodiments, parameters of the tape drivemay be used to identify the initial corrosion incident which may then berecorded, and the cause of which may be searched for. Thus, warningsystems and/or more complete records of the performance and functionalparameters for a given tape drive may aid in reducing the number offailures experienced, as will be described in further detail below.

It follows that various embodiments described herein may collect datarelevant to the performance and/or health of a given tape drive.Moreover, depending on the type of data collected, it may be used toimprove tape drive performance in different ways as will soon becomeapparent.

Looking to FIG. 8A, a flowchart of a method 800 is shown according toone embodiment. The method 800 may be performed in accordance with thepresent invention in any of the environments depicted in FIGS. 1A-7,among others, in various embodiments. Of course, more or less operationsthan those specifically described in FIG. 8A may be included in method800, as would be understood by one of skill in the art upon reading thepresent descriptions.

Each of the steps of the method 800 may be performed by any suitablecomponent of the operating environment. For example, in variousembodiments, the method 800 may be partially or entirely performed by acontroller, a processor, etc., or some other device having one or moreprocessors therein. According to a specific example, one or more of theprocesses of method 800 may be implemented by a computer. Thus, method800 may be a computer-implemented method. The processor, e.g.,processing circuit(s), chip(s), and/or module(s) implemented in hardwareand/or software, and preferably having at least one hardware componentmay be utilized in any device to perform one or more steps of the method800. Illustrative processors include, but are not limited to, a centralprocessing unit (CPU), an application specific integrated circuit(ASIC), a field programmable gate array (FPGA), etc., combinationsthereof, or any other suitable computing device known in the art.

As shown in FIG. 8A, operation 802 of method 800 includes collectingperformance data corresponding to a tape drive and/or one or moremagnetic tape heads. The type of performance data collected may varyaccording to different embodiments. For instance, the performance datacollected may be based on a user's request, pre-identified types ofdata, performance conditions, analysis of data already collected, areasof interest, specific applications of the tape drive and/or magnetictape head(s) included therein, etc., depending on the desiredembodiment. According to an example, a tape drive designed for aparticular application (e.g., based on user specifications) may bepreset to collect certain performance data which corresponds to theapplication for which it was designed.

According to various approaches, the performance data collected inoperation 802 may include any one or more of: a current and/or a voltageapplied to one or more transducers in a magnetic tape head, a SNR, a C1and/or C2 BER, a resistance of a read sensor in a magnetic tape head,resistance of data and/or servo elements, a read-back amplitude of theread sensor, asymmetry of the read-back amplitude, a number of rewriteattempts performed by a write transducer in a magnetic tape head, a dataquantity written to tapes, a PW50 head-tape-spacing, capacity loss,whether the magnetic orientation of a magnetic layer (e.g.,Antiferromagnet) is reversed for one or more of the transducers (e.g.,for a GMR, AMR, etc. sensor), asymmetry, whether a short has occurred ina Reader, a number and/or a frequency of write temporary errors, anumber and/or frequency of permanent errors, a data transfer rate, thedata read-write rates, the time to write the data on a tape, the numberof tapes on which data has been written, a resistance of the Readers andWriters in the magnetic tape head(s), a resolution of the read-backsignals for the Readers in the tape drive and/or the magnetic tapehead(s), the stripe height (SH) of the Read sensors etc. It should benoted that the aforementioned list of potential performance data typesis in no way intended to be limiting, and may include any other type(s)of performance data and/or functional parameters which would be apparentto one skilled in the art upon reading the present description.According to a preferred approach, the performance data collected inoperation 802 is sufficient to reconstruct when a change in theperformance of the tape drive and/or the read and/or write elements of amagnetic tape head in the tape drive occurred.

For clarification, several of the aforementioned performance parameterswill be defined:

C1BER: BER of an individual channel of the drive

C2BER: Overall BER for all data channels of the drive

SH: Height of the Reader in the direction perpendicular to the TapeBearing Surface (TBS)

1F: highest frequency (inverse length) of the data

2T: 2× the transition length of 1F

8T: 8× the transition length of 1F

Amplitude: Vmax+Vmin, where Vmax is the magnitude of the maximumpositive read voltage and Vmin is the magnitude of the maximum negativevoltage

Asymmetry: (Vmax−Vmin)/Amplitude

Resolution: Ratio of Amplitude at two different frequencies, e.g.Amplitude(2T)/Amplitude(8T)

Head-Tape Spacing: Distance between the read transducer at the TBS andthe magnetic tape surface

PW50: Half amplitude pulse width, or width of the written data at halfthe peak amplitude

Capacity: Amount of data stored in a tape cartridge, e.g. 1 TB or 20 TBto fill the tape cartridge, etc.

Wrap: Data is written to a tape cartridge by running tape across a headfrom a physical beginning of tape (BOT) to end of tape (EOT) and allWriters write simultaneously to a data track. One pass from BOT to EOTis a Wrap

Full File Pass (FFP): A tape cartridge can be filled with a specificnumber of Wraps, call that Nwrapmax. Running Nwrapmax Wraps is termed aFFP.

The process of collecting the performance data may also vary dependingon the type of performance data being collected. According to someapproaches, collecting the performance data includes collectingperformance data from all of the transducers included in a tape drive.In other approaches, performance data may only be collected from asubset of all transducers included in a tape drive. Further still,different types of performance data may be collected from differentsubsets of the transducers in a tape drive. Subsets of transducers maybe determined based on a level of performance, a health of thetransducers, an evaluation of already collected performance data,specified conditions, etc. It follows that types of data collectedand/or the transducers for which the performance data is collected mayvary and be updated as performance changes over time. The performancedata is preferably collected multiple times during the use of the tapedrive which may be specified by real time intervals, different use timeintervals, such as tape usage intervals, specific conditions of thedrive performance, etc. Moreover, in some approaches all data which iscollected may be stored in memory, while in other approaches, only asubset of the data collected may actually be stored in memory, e.g., seeFIG. 10 below.

With continued reference to FIG. 8A, method 800 also includes storingthe performance data in memory. See operation 804. As mentioned above,the performance data is preferably stored for use in performing problemanalysis, e.g., predicting whether the tape drive and/or magnetic tapeheads have performance issues, e.g., as will be described in furtherdetail below. Depending on the desired approach, some or all of thecollected performance data may be stored on a hard drive, on adesignated tape cartridge, on a non-volatile random access memory drive(e.g., Flash memory) in the tape drive and/or server external to thetape drive, on a secure external intranet accessible storage site, etc.For approaches implementing data storage at locations external to thetape drive, the tape drive and external memory location may bepartitioned, e.g., for access by a tape drive service team. Moreover,implementing a firewall between the tape drive customer data and thetape drive service team data may be desired, e.g., with encryption ofthe data.

Operation 806 of method 800 further includes using the data to performproblem analysis for the tape drive and/or magnetic tape head(s).According to preferred approaches, the problem analysis includespredicting future failure conditions of the tape drive and/or themagnetic tape head. It should be noted that a failure condition is notlimited to total failures of the tape drive and/or magnetic tapehead(s). Rather, according to different approaches, a failure conditionmay include a partial failure, e.g., a failure of one or more individualtransducers, inoperability of one magnetic tape head in a tape drive,etc.; a total failure, e.g., complete inoperability of the tape drive; adrop in data storage capacity below a specific limit (which may be setat the maximum allowed by the cartridge or some percentage of themaximum allowed); excessive amount of data rewrites or rewrite rates; aminimum BER; etc., depending on the desired embodiment. Problem analysismay be performed by a user (e.g., human analysis of the provided data),automated in the tape drive code, performed by a computer, etc.Moreover, in some approaches, problem analysis may be improved byimplementing a learning curve which couples stored data with adetermined failure mechanism as would be appreciated by one skilled inthe art upon reading the present description.

Referring now to FIG. 8B, sub-operations corresponding to theperformance of operation 806 are shown according to one embodiment. Thesub-operations of FIG. 8B may be performed in accordance with thepresent invention in any of the environments depicted in the otherFIGS., such as FIG. 8A, among others, in various embodiments. Of course,more or less operations than those specifically described in FIG. 8B maybe included in the sub-operations illustrated therein, as would beunderstood by one of skill in the art upon reading the presentdescriptions.

As shown, operation 806 may include tracking changes to the performancedata over use time. See sub-operation 806 a. A useful concept is usetime, which is a measure of the usage of the drive. Examples of use timeare: time since the drive was manufactured; time the drive has beenpowered on; number of tape cartridges mounted onto the drive; number ofFFP for either data read-only passes or for data write passes; amount ofdata written to or read from tape; etc.

Tracking changes to the performance data may include changing a samplingrate of the performance data, flagging subsets of the stored performancedata, making a duplicate copy of a subset of the performance data,sending a notification to a user, etc., e.g., in response to satisfyinga condition (e.g., see FIG. 10B below). According to some approaches,performing the problem analysis may include reconstructing when a changein performance of the tape drive and/or the magnetic tape head(s)occurred. Thus, by tracking changes to the performance data over usetime, the ability to reconstruct when a certain change occurred may bepossible at a future point in use time.

Moreover, sub-operation 806 b includes extrapolating (e.g., predicting)future failure conditions of the tape drive and/or the magnetic tapehead from the tracked changes in the performance data. According to anexample, a resistance of a magnetic head may be used to perform problemanalysis and extrapolate future failure conditions. Tape drives aredesigned to be robust to ranges of amplitudes of the device and rangesof signal-to-noise ratios (SNR). Accordingly, BER may not be negativelyaffected until amplitudes and/or SNR are below a given level (e.g., athreshold). Therefore, by collecting changes in the performance dataover use time, e.g., such as R_(head), SNR, amplitudes of the device,etc., an extrapolation may be made as to when certain performance datais expected to drop below a critical value. Thus, predicted (e.g.,projected) failure conditions may be determined well before poor BERsare experienced or a drop in data storage capacity.

Referring momentarily to of FIG. 9, graph 900 illustrates a simulatedplot of amplitude and BER versus time. As shown, while the Amplitude isdropping steadily and predictably, the BER is not affected until theAmplitude falls below a normalized amplitude of about 0.5, at whichpoint the BER begins to drop rapidly. Where the plots for Amplitude andBER meet represents a resulting failure (as indicated in graph 900) inthe corresponding tape drive. It follows that, by studying theconnection between the Amplitude and BER plots, the steady drop inAmplitude may be used to project when the BER will begin to degrade,even at a point in time when the BER is at a steady, desirable value. Itfollows that the potential issues associated with the amplitude loss canbe predicted sooner and more accurately using the Amplitudecorresponding to a given embodiment, either alone or in conjunction withthe corresponding BER.

Thus, it should again be noted that a failure condition is not limitedto total failures of the tape drive and/or magnetic tape head(s).Rather, according to different approaches, a failure condition mayinclude a partial failure, e.g., a failure of one or more individualtransducers, inoperability of one magnetic tape head in a tape drive,etc.; a total failure, e.g., complete inoperability of the tape drive;etc. By extrapolating future failure conditions, actions may be taken inanticipation of the failure conditions which may prevent the effects ofsuch conditions, e.g., by examining a current condition of the tapedrive and/or magnetic tape head(s), as will soon become apparent.

Moreover, an important aspect of using performance data includesevaluating past data in addition to present data. The current state of atape drive is often collected and stored periodically over a period oftime. As described above, performance data pertaining to a tape drivemay be collected at an inception of the tape drive (e.g., seeDump_(timeIntial) above) and also stored. Thus, tape drive performancedata from an initial point in time may be compared against performancedata from a current point in use time to determine a state of the tapedrive and/or project future failure conditions. For example, if amagnetic head included in a tape drive is wearing with use time and theread amplitude in reader(s) of the magnetic head is dropping, the rateat which the amplitude drops may be used to extrapolate a future failurecondition.

Accordingly, with continued reference to FIG. 8B, sub-operation 806 cincludes determining a current functional status of the tape driveand/or the magnetic tape head(s). As mentioned above, the current statusof the tape drive and/or the magnetic tape head may be used incombination with past performance data and future failure analysis inorder to assist in preventing the effects of future failure conditions.Accordingly, sub-operation 806 d includes determining (e.g.,calculating) an amount of use time of the tape drive and/or the magnetictape head between a current point in use time associated with thecurrent status and one or more of the future failure conditions. Inother words, sub-operation 806 d may determine a number of tape runs,write operations, tape mount operations, an amount of real time, etc.,between a current point in use time and each of the extrapolated futurefailure conditions (at a later use time). Note, as described above, thatthe user can utilize various metrics to represent the use time whichseparates a current point in use time and each of the future failureconditions, e.g., depending on the desired embodiment.

According to one approach, the collected performance data may be used todetermine the current functional status of the tape drive and/or themagnetic tape head(s) by comparing the performance data to a rangeseparating acceptable (e.g., good) and unacceptable (e.g., bad) statusfor the tape drive and/or magnetic tape head(s). Thus, the tape driveand/or magnetic tape head(s) may be deemed acceptable (e.g., healthy) inresponse to the performance data falling within a certain range, andalternatively unacceptable (e.g., unhealthy) in response to theperformance data falling outside the range. It should be noted that“within a certain range” and “outside the range” are in no way intendedto limit the invention. Rather, than determining whether the performancedata is within or outside a certain range, equivalent determinations maybe made, e.g., as to whether the performance data is above a threshold,below a threshold, having an absolute value above a threshold, having anabsolute value within a range, etc., depending on the desired approach.

According to a specific example, which is in no way intended to limitthe invention, Equation 1 may be used to predict a future failurecondition with respect to “x”, where x represents the use time, whichmay be the amount of real time since the drive was manufactured, thetime the drive has been powered on, a number of tapes mounted onto thedrive, a total number FFP, a total amount of data written, etc., or someother measure of use.

f ₁(x)=a _(o) +a ₁ *x   Equation 1

Here, a_(o) and a₁ are fitted parameters for fitting the collected dataas would be appreciated by one skilled in the art upon reading thepresent description. Again, by fitting the collected performance data toa monotonically changing function as shown in Equation 1, a futurefailure condition with respect to x may be determined.

According to a similar example, a quadratic equation may be used, e.g.,as shown in Equation 2.

f ₂(x)=a _(o) +a ₁ *x+a ₂ *x ²   Equation 2

Again, a_(o) and a₁, as well as a₂ are fitted parameters, as would beappreciated by one skilled in the art upon reading the presentdescription.

In another example, an exponential equation may be used to predict afuture failure condition with respect to “x”, as shown in Equation 3.

f ₃(x)=F+D*e ^((c*x))   Equation 3

where c, D and F are fitted parameters, as would be appreciated by oneskilled in the art upon reading the present description.

According to another example, a stretched exponential equation may beused to predict a future failure condition with respect to “x”, as shownin Equation 4.

f ₄(x)=F+D*e ^((c*x) ^(b) ⁾   Equation 4

Again, c, D and F, as well as b are fitted parameters.

In yet another example, a combination of Equations 5.1-5.4 may be usedin combination with Equations 1-4 respectively, to predict a futurefailure condition with respect to “x”.

G ₁ *f ₁(y ₁)   Equation 5.1

G ₂ *f ₂(y ₂)   Equation 5.2

G ₃ *f ₃(y ₃)   Equation 5.3

G ₄ *f ₄(y ₄),   Equation 5.4

Here, y_(j)=x−x_(jo), where G_(j)=0 for x<x_(jo), and G_(j)=1 forx≧x_(jo). Alternatively, G_(j)=0 for x≧x_(jo), and G_(j)=1 for x<x_(jo).Furthermore, D, F, c, b, G_(j) and x_(jo) are fitted parameters, aswould be appreciated by one skilled in the art upon reading the presentdescription.

It should again be noted that the above examples are presented by way ofexample only, and are in no way intended to limit the invention. Rather,other functions may be used to determine a future failure condition,e.g., when a performance data parameter will fall outside an acceptablerange as described above.

Referring again to FIG. 8B, sub-operation 806 e includes outputting awarning, e.g., to a user, in response to determining the expected amountof use time between the current point in use time and a projected realtime when any of the future failure conditions is projected to be lessthan a threshold. The expected amount of use time may be predefined,calculated using known methods, updated based on performance data, etc.It should be noted that “less than a threshold” is in no way intended tolimit the invention. Rather, than determining whether a value is lessthan a threshold, equivalent determinations may be made, e.g., as towhether the performance data is above a threshold, within or outside acertain range, having an absolute value above a threshold, having anabsolute value within a range, etc., depending on the desired approach.

A threshold may be measured based on the amount of use of the tape driveand/or the magnetic tape head between a current point in use timeassociated with the current status and one or more of the future failureconditions. According to different approaches, a warning may be outputin response to the amount of use dropping a factor Df below an initialamount. Df may be any percentage between 100% and 0% which themanufacturer of the tape drive or the user of the tape drive chooses asa limit based on an effective lifetime of the tape drive. For example, auser may choose a value of 75% for Df with Capacity being the metric ofchoice. Through statistics, it may be determined that if M of the totalN tracks have a C1BER below some clip level, then the drive capacitywill fall below 75%, then one might use the degradation of C1BER toproject the failure use time point. Similar calculations may be doneusing SNR or and SNR equivalent. If a tape drive continues to operatedespite one or more warnings being output, the tape drive may bequarantined (e.g., purposefully deactivated) in response to the amountof use between a current point in use time and one or more futurefailure conditions falling below a critical level, e.g., a Df value of75% of an initial amount of use based on an effective lifetime of thetape drive. A separate warning may be sent, e.g., to a user, to indicatethat the tape drive has been quarantined and that replacement and/orrepair of the quarantined tape drive is desired before read and/or writerequests may be performed.

As an example, assume that it is determined that if a drive has 8 trackswith C1BER below 1000 bit-per-error then the drive capacity will fallbelow 75%, and 3 tracks have fallen below 1000 bit-per-error with a rateof 1 per 50 FFP, and Equation 1 is able to fit the data, where f1 is thenumber of tracks below 1000 bit-per-error, and ao=0 and a1= 1/50 FFP⁻¹,then the algorithm may project a failure at x=400 FFP. Along with theuse time, a projected real time can be calculated based on past usage.In the example above, if the drive has been performing 21 FFP/week, thenthe failure point can be projected to be 5*50 FFP/(21 FFP/week) or 11.9weeks.

The warning output may include the amount of use time between thecurrent point in use time and any of the future failure conditions, inaddition to the predicted points in use time that each of the failureconditions will occur. Thus, appropriate steps may be taken in order topostpone and/or prevent the effects of the future failure conditions. Itshould be noted that in different approaches, other metrics may be usedto quantify a separation between a current state and any of the futurefailure conditions, e.g., such as number of tape runs, resistance, atotal number of full tape cartridges written to, an amount of time sincemanufacture, a total amount of data written, etc.

In further approaches, the warning may indicate an inferred cause of thegiven failure condition. For example, sub-operation 806 e may includegenerating and/or outputting a specific fault-symptom code deduced fromthe performance data available, and which identifies one of corrosion,wear, debris buildup, damaged wiring, sensitivity loss, electricalshorts, excessive noise, etc. as the cause of the failure condition.Accordingly, a recipient of the output warning may be provided with aninitial evaluation of the available performance data such thatappropriate subsequent action may be performed to prevent and/or delaythe failure condition.

According to some approaches, a warning output in sub-operation 806 emay be posted to the tape drive, e.g., as a fault error symptom code.

By maintaining a history of the performance data for a tape drive,determinations as to when a particular issue arose may be made. Forexample, if previously stored performance data reveals that theresistance of some readers in a magnetic tape head had risen more thancan be ascribed to wear, then corrosion, wire bond or lead crackingissues may be ascribed as the cause of the rise in resistance.Accordingly, the tape drive may send an alert (e.g., to a user,administrator, manufacturer, maintenance entity, etc.) that a corrosiveagent may be present in the tape drive. By using further information,such a humidity or whether writers also have increased resistancechanges, then the drive may be able to narrow the likelihood of whethercorrosion or mechanical problems with the leads is the culprit. Addingstatistical data from other libraries or failure analysis (FA) on otherdrives can assist in determining the probability of corrosion vsmechanical lead issues. This rapid warning system may be able topreserve resources by alerting a user to perform corrective actions.Collection and storage of other parameters such as temperature, relativehumidity (RH) and tape usage may further assist in trouble shooting theproblem before its effects compromise the performance of the tape drive.

As mentioned above, sub-operations corresponding to the performance ofoperation 806 may include various processes, e.g., depending on thedesired embodiment. The sub-operations included therein may determinewear and/or corrosion of the tape drive and/or the magnetic tape headaccording to different approaches. In some approaches, wear and/orcorrosion of the tape drive and/or the magnetic tape head may bedetermined using wear rates and/or asymptotic values thereof.

In other approaches, wear and/or corrosion of the tape drive and/or themagnetic tape head may be determined using resistance of the tape driveand/or magnetic tape head(s). Thus, an effective stripe height of one ormore transducers on the magnetic tape head and/or an effective magneticspacing between one or more of the transducers and a magnetic tape maybe calculated in some embodiments. Furthermore, an indication of wearmay be output in response to determining that the effective stripeheight has changed and the effective magnetic spacing has changed for agiven transducer, and the amount of the change in the calculated SH andthe spacing are consistent with one another and with previously-detectedchanges which were verified through FA to be wear. Moreover, anindication of accumulation on the magnetic tape head may be output inresponse to determining that the effective magnetic spacing hasincreased while the effective stripe height has not changed sufficientlyto account for the increase in spacing.

An effective stripe height of transducers may be calculated using theresistance and/or resolution thereof. According to one example, theresistance of the sensor of a magnetic tape head may be used todetermine the stripe height (SH) of a given current-in-plane (CIP)sensor on the magnetic tape head using Equation 6 below.

SH=R _(sheet) *W/R _(head)  Equation 6

R_(head) represents the resistance of the sensor, e.g., with externalcable, wire, lead, etc., resistances subtracted away, for which the SHis being determined. Moreover, R_(sheet) represents a sheet resistance,and W represents a corresponding width of the sensor measured in a trackwidth direction.

Similarly, Equation 7 may be used to determine the stripe height (SH) ofa given current-perpendicular-to-plane (CPP) sensor on the magnetic tapehead having a known resistance-times-area, RA.

SH=RA/(W*R _(head))   Equation 7

As alluded to above, in other approaches, wear and/or corrosion of thetape drive and/or the magnetic tape head may be determined usingresolution of the tape drive and/or magnetic tape head(s). According toone example, the spacing between the media facing surface of the tapehead, and a surface of the magnetic tape may be calculated usingEquation 8 which implements the corresponding resolution Res of themagnetic head.

Res(λ₁,λ₂)=Amp(λ₂)/Amp(λ₁)   Equation 8

Here, λ₁ and λ₂ represent two data wavelengths, where λ₂<λ₁. Thus,Res(λ₁,λ₂) represents the ratio of the read-back amplitude at twodifferent data wavelengths. Alternatively, Res(λ₁,λ₂) may be representedin terms of Wallace spacing losses as shown in Equation 9, where drepresents the spacing.

Res(λ1,λ2)=e ^((−2*π*d*((1/λ2)−(1/λ1))))  Equation 9

As mentioned above, performance information (e.g., data) may be used todetermine the corrosion and/or wear of the one or more transducers onthe magnetic tape head. According to some approaches, resistance and/orresolution data may be used to determine an amount of wear experiencedby transducers. For example, an increased resistance may indicate wearon a given transducer, e.g., resulting from tape being run thereover. Inanother example, a SH less than an initial height of the sensor (e.g.,before being used) may indicate an amount of wear has occurred on atransducer. In the case of wear, the resistance changes limited by themaximum wear achievable. For example a large wear may recess the reader30 nm. For a reader with a SH of 600 nm, this corresponds to about a 5%increase in reader resistance. For older generations of magnetic media,an upper limit in wear might be 40 or 50 nm, or about 7 to 9%. In mostcases, wear will affect all read elements. Newer generations of magneticmedia will need to have even lower limits in wear. It follows thatamounts of wear may be “learned” for, e.g., correlated with, a givenmedia type and/or generation. Moreover, embodiments having wear mayexperience a localized increase in transducer resistances. Moreover,effects resulting from wear may follow a limited wear rate, e.g., whichmay be determined by experiments. In some approaches, wear may beverified by estimating the spacing between the media facing surface ofthe tape head and a surface of the magnetic tape. The spacing may becalculated from the resolution data, e.g., such that the change inspacing from before being used, to the current state should be at leastsimilar to the change in SH experienced over the same period.

Similarly, resistance and/or SH data may be used to determine corrosionof transducers on magnetic tape head(s). For example, the effects ofcorrosion may be detected, and an amount of corrosion may be measured,in response to determining that the resistance is greater than and/orthe SH is less than, an initial amount for a given transducer (e.g.,before being used). When a reader corrodes, the resistance will increaseand the amplitude will decrease. Mild corrosion may result in smallchanges in resistance, such as a fraction of a percent or a single digitpercentage. As the corrosion progresses, the resistance change couldincrease indefinitely. Thus corrosion can be distinguished from wear bycomparing the level of the resistance changes, the standard deviation inthe resistance changes, whether all or some of the readers haveresistance changes, and also using the resolution.

Corrosion of the material included in a transducer may result in agreater amount of effective SH decrease and/or resistance increase incomparison to the effects caused by wear of a transducer. Thus, theresistance of a corroding transducer may increase to a complete opencircuit in some approaches. In other approaches, the effective SH of acorroding transducer may reach a value of zero. Furthermore, forcorroding transducers, the distribution of changes to resistance and theeffective SH calculated from the change in resistance may vary bygreater amounts than experienced as a result of transducer wear, and maytherefore fall outside wear rate predictions. Thus, the corrosiondetermined for each sensor of a magnetic tape head may be averagedacross the tape head, e.g., to determine an overall amount of corrosionfor the tape head as a whole.

According to another embodiment, operation 806 may include identifyingelectrical shorts in one or more transducers on the magnetic tape head.Upon shorting, a transducer may be rendered useless, e.g., a shortedread transducer may no longer be able to read data from a magneticmedium. Thus, it is desirable to detect and identify shorted transducersfor replacement, compensation, to inform a user, etc. According to someapproaches, resistance and/or resolution data may be used to determineshorting of transducers. For example, embodiments having TMR sensors mayexperience a short across the thin tunnel junction, while embodimentshaving CIP MR devices (e.g., such as AMR, GMR etc. sensors) mayexperience a short between the magnetic shields and the MR sensor. Ashort may be identified when the resistance of the transducer decreasesfrom its original value. However, the resolution of a shorted transducershould not be affected by the short. According to an illustrativeembodiment, which is in no way intended to limit the invention, theamplitude response for a TMR sensor at a fixed voltage may not decreaseby more than about 10% to about 20%, but could be higher or lower.

In other embodiments, operation 806 may include determining theaccumulation of an insulating material on a tape bearing surface of theone or more transducers. During use, transducers on a magnetic tape headmay gradually accumulate a layer of insulating material. Although theresistance of the transducers may not be affected by the accumulation ofan insulating material on the media facing side thereof, the thicknessof the deposited material may directly decrease the amplitude andresolution of the transducer, e.g., corresponding to the Wallace spacingloss, as would be appreciated by one skilled in the art upon reading thepresent description. Thus, resolution data may be used to calculate athickness of an insulating material deposited on a media facing side ofone or more transducers. According to one example, detecting lowresolution for the read-back signal corresponding to a data trackwritten by a poorly performing writer may result in the determinationthat the writer has undergone corrosion and/or has accumulated material(e.g., insulating material) on a media facing surface thereof. Upondetermining that an insulating material has accumulated on a tapebearing surface of the one or more transducers, identifying the one ormore transducers for replacement, for compensation, for cleaning, toinform a user, etc., may be desired.

The accumulation of other materials on the media facing surface of oneor more transducers may also be identified. According to differentapproaches, changes in resolution, changes in magnetic amplitude, PW50increases, SNRa decreases, etc. may indicate Wallace spacing losseswhich may be identified with the accumulation of material on the mediafacing surface of one or more transducers. Moreover, the accumulation ofother materials on the media facing surface of one or more transducersmay not flip the magnetic orientation of layers in GMR transducers.

Further embodiments may include determining that sensors are undergoingdegradation from some form of damage to the surface of the sensor. Ifthe resolution of a few readers decreases significantly below the levelof the median of all readers and the calculated stripe height increasesan amount consistent with the decrease in resolution, then something isdamaging the surface portion of the degraded readers to the level of thecalculated spacing and SH change. This source of the damage could becorrosion, either from an external corrosive agent or from oxidation ofthe surface of the sensor from a form of head-tape-interface generatedthermal oxidation.

Further still, in other embodiments, operation 806 may includeidentifying a mechanical bond issue. Mechanical bonding issues maydevelop over time and have a significant effect on the performance of amagnetic tape head. The resistance of a magnetic tape head may be usedto determine the presence of a mechanical bond issue, e.g., for an arrayof transducers. According to some approaches, if the resistance ofseveral adjacent transducers of a magnetic tape head increase while theresistance of the remaining transducers in the head do not substantiallychange, then it may be determined that damage to the electrical bondingof the transducers to the corresponding cables has occurred. Moreover,the drive code may record a fault symptom code associated withmechanical bonding issue in response to determining that a mechanicalbonding issue has occurred.

It follows that any one or more of the processes which may be performedas a part of operation 806 may be used in predicting future failureconditions of the tape drive and/or the magnetic tape head, e.g., usingthe information obtained as a result.

Generally, there are a significant number of read and/or writetransducers (e.g., elements) included in a given tape drive. This allowstape drives to operate successfully even with less than all of the readelements functioning successfully. Further still, tape drives implementmagnetic heads which are in direct contact with the media at a mediafacing side thereof. Thus, wear is an integral part of a tape drivewhich is preferably taken into account when performing problem analysis,e.g., to predict future failure conditions.

However, as described above, tape cartridges have a limited amount ofmemory available to store data. Moreover, there may be a significantnumber of read and/or write transducers included in a given tape drive.Thus, storing a condensed amount of the collected performance data maybe preferred in some embodiments.

Looking to FIG. 10A, method 1000 illustrates a flowchart for condensingthe collected performance data in accordance with one embodiment. Themethod 1000 may be performed in accordance with the present invention inany of the environments depicted in FIGS. 1-8C, among others, in variousembodiments. Of course, more or less operations than those specificallydescribed in FIG. 10A may be included in method 1000, as would beunderstood by one of skill in the art upon reading the presentdescriptions.

Each of the steps of the method 1000 may be performed by any suitablecomponent of the operating environment. For example, in variousembodiments, the method 1000 may be partially or entirely performed by acontroller, a processor, etc., or some other device having one or moreprocessors therein. The processor, e.g., processing circuit(s), chip(s),and/or module(s) implemented in hardware and/or software, and preferablyhaving at least one hardware component may be utilized in any device toperform one or more steps of the method 1000. Illustrative processorsinclude, but are not limited to, a central processing unit (CPU), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), etc., combinations thereof, or any other suitablecomputing device known in the art.

As shown in FIG. 10A, operation 1002 of method 1000 includes collectingperformance data corresponding to a tape drive and/or a magnetic tapehead from all of the transducers on the magnetic tape head, or acombination thereof. According to a preferred approach, the performancedata is collected sequentially in time, e.g., at intervals, upon userrequest, upon meeting a predetermined condition, etc. Moreover,operation 1004 includes condensing the collected performance data toreduce a size of the collected performance data stored to memory, e.g.,by performing down sampling, while operation 1006 includes storing thecondensed performance data in memory, preferably in a structuredatabase. Collected performance data may be condensed by implementingany one of a number of processes, as will soon become apparent.

According to various approaches, condensing the collected performancedata may include calculating a mean value of the performance data, amedian value of the performance data, a standard deviation of theperformance data, a minimum value of the performance data, a maximumvalue of the performance data, a number of tracks whose values for agiven parameter are outside of a predetermined range, a number of trackswhose values deviate from the mean or median by a predetermineddeviation, etc., and/or combinations thereof. In another approach, thefrequency at which performance data is collected may be changed, e.g.,to reduce an amount of performance data at issue. In other approaches,condensing the performance data may include maintaining a rollingaverage of the performance data in memory, e.g., to lessen the effectsof temporary tape drive errors. According to an example, which is in noway intended to limit the invention, a rolling average may include themost recent “N” measured data sets, where the first N collected datasets will be stored in bins B(1) through B(N). Moreover, the “N+m” dataset (m=1 to N) will be stored in bin B(m), and data set “p” will bestored in bin B(q), such that q=p−N*floor((p−1)/N), where floor(x)rounds x down to the nearest integer, as would be appreciated by oneskilled in the art upon reading the present description.

Table 1 below shows a rolling average calculated for data collectedthrough 24 sets. As illustrated, data is stored in bins B1 through B10,and the rolling average having n=24 is taken from {D15 to D24}, as wouldbe appreciated by one skilled in the art upon reading the presentdescription. Accordingly, when data D11 through D20 are collected, theysequentially overwrite data in bins B1 through B10 respectively.

TABLE 1 Bin Pass B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 Average 1st D1 D2 D3 D4D5 D6 D7 D8 D9 D10  D1:D10 2nd D11 D12 D13 D14 D15 D16 D17 D18 D19 D20D11:D20 3rd D21 D22 D23 D24 D15 D16 D17 D18 D19 D20 D15:D24Note that the rolling average needs to be continually recalculated. Inthe case of replacing bin Bq with the value Dp. Assume that Dq-old isthe value currently in bin Bq which will be replaced with the value Dp.Also assume that the rolling average, RollAveOld is current rollingaverage, then the updated rolling average, RollAveNew is:

RollAveNew=RollAveOld+(Dp−Dq)/N.   Equation 10a

The new standard deviation, STDNew, can then be calculated from theprevious standard deviation, STDOld by:

STDNew²=STDOld²+(Dp ² −Dq ²)/N−2*(RollAveNew²−RollAveOld²)/N.   Equation10b

Referring still to FIG. 10A, operation 1008 includes using the condensedperformance data to perform problem analysis. According to variousapproaches, performing the problem analysis of operation 1008 mayinclude any of the processes described herein. In one approach, theproblem analysis may include predicting future failure conditions of thetape drive and/or the magnetic tape head, e.g., using the informationobtained by any one or more of the sub-operations in FIGS. 8B-8C. Inanother approach, the problem analysis may include reconstructing when achange in performance of the tape drive and/or the magnetic tape headhas occurred in the past, e.g., using tracked changes in the performancedata.

As mentioned above, condensing performance data may include a number ofdifferent processes. Looking now to FIG. 10B, sub-operationscorresponding to the performance of operation 1004 are shown accordingto one embodiment. The sub-operations of FIG. 10B may be performed inaccordance with the present invention in any of the environmentsdepicted in the other FIGS., such as FIG. 10A, among others, in variousembodiments. Of course, more or less operations than those specificallydescribed in FIG. 10B may be included in the sub-operations illustratedtherein, as would be understood by one of skill in the art upon readingthe present descriptions.

As shown, the sub-operations of operation 1004 may include receiving anew set of the collected performance data and overwriting the previousmost recent data, and comparing values of the collected performance datawith corresponding values of most recent data points of existingperformance data. See sub-operations 1004 a and 1004 b. It follows thatthe existing performance data may already be stored in the memory, e.g.,in a permanent (non-transitory) register.

Looking to decision 1004 c, it is determined whether a differencebetween each of the values of the collected performance data and each ofthe corresponding values of the most recent data points of the existingperformance data are within a range. As illustrated, the process shownin FIG. 10B returns to operation 1004 a in response to determining thata difference between a given value of the collected performance data anda corresponding value of the most recent data points is within therange.

Alternatively, the process shown in FIG. 10B proceeds to operation 1004d in response to determining that a difference between a given value ofthe collected performance data and a corresponding value of the mostrecent data points is not within the range. In operation 1004 d, thegiven value of the collected performance data is stored permanently inmemory, and is stored as a new most recent data point, thereby replacingthe previously most recent data point. By “stored permanently” in thiscontext, what is meant is that the data is stored and is not overwrittenby other operations in process 1004. Such data may be copied, deletedand/or overwritten at a later time, such as upon storing on an externalstorage media and performing a failure analysis, re-initiation ofprocess 1000 of FIG. 10A, reboot of the drive, replacing the defectivecomponent, such as a defective head, etc. Note that values that are“temporarily” stored, such as the most recent data, may be overwrittene.g., in operation 1004 a.

It follows that only collected performance data that varies from apreviously stored value greater than a predetermined amount is storedpermanently in memory. As a result, the limited amount of availablememory is desirably not used to simply store redundant copies ofperformance data. Rather, by limiting the amount of data stored to onlyinclude the collected performance data which deviates from a last storedvalue by a certain amount, important transitions in performance may beselectively stored. Thus, a current status of the tape drive and/or themagnetic tape head may be determined by comparing collected performancedata with a predetermined range.

One problem with a rolling average approach is that earlier data islost. One can be creative and combine techniques. For example, one couldcombine a rolling average with a permanent data set. That is, if thedifference in the value of a parameter exceeds a certain number, thenthat rolling average is added to the permanent stored data. The rollingaverage continues to be taken in the rolling average bins, but a secondstorage file contains the information whenever large changes haveoccurred, and those data sets are not overwritten.

As previously mentioned, the range may separate acceptable (e.g., good)and unacceptable (e.g., bad) performance data for the tape drive and/ormagnetic tape head(s). However, it should be noted that “within acertain range” and “outside the range” are in no way intended to limitthe invention. Rather, than determining whether the performance data iswithin or outside a certain range, equivalent determinations may bemade, e.g., as to whether the performance data is above a threshold,below a threshold, having an absolute value above a threshold, having anabsolute value within a range, etc., depending on the desired approach.

In other words, the processes described in FIGS. 10A-10B may be used todetermine whether collected data should be stored in memory. Asmentioned above, data may be collected on a regular basis, upon request,when specific conditions have been met (e.g., when certain parametersare to be recalibrated), etc. However, a data value may only actually bestored if the collected value has changed from a correspondingpreviously stored value by at least a given amount. Then the collecteddata value may overwrite the temporary data. Moreover, the collecteddata value may be stored permanently if the value has changed from thecorresponding previously stored value by more than a specified amount.For example, if Pn represents the nth permanently stored value, while“T” represents a temporary stored current value, then with respect tothe case of N permanent stores, the data may be represented as P(1), . .. , P(N),T. It follows that, if the change is large enough, then the newdata is stored both as P(N+1) as the temporary stored value T, wherebythe data may be represented as P(1), . . . , P(N), P(N+1), such thatP(N+1)=T. Moreover, it is preferred that all stored data is tagged bothfor real and use time.

According to another example, which is in no way intended to limit theinvention, the processes of FIGS. 10A-10B may be used to measure andrecord performance parameters and use parameters for a tape drive havingmultiple read and/or write channels. Moreover, the processes of FIGS.10A-10B may be able to record the number of read and/or write channelswhich exceed a pre-determined clip performance value “N_(poor)” and themeasure of use “x” at which each channel is anticipated to exceed theclip performance value. Clip performance values N_(poor) may be plottedon a graph with respect to the measure of use x. A monotonicallychanging function as shown in Equation 11 may be used to extrapolate aprojected time for failure.

$\begin{matrix}{{N_{poor}(x)} = {1 - {\exp \left( \left( \frac{t}{td} \right)^{\beta} \right)}}} & {{Equation}\mspace{14mu} 11}\end{matrix}$

Here τ and β are fitting parameters as would be appreciated by oneskilled in the art upon reading the present description.

In another example, which is again in no way intended to limit theinvention, data already stored in memory (e.g., the most recent datapoints of the existing performance data) may have permanently storeddata sets, {P(1), P(2), . . . , P(N)}, where there are N permanentlystored data sets. Moreover, the newly collected performance data setsmay be stored in temporary data storage locations “T”. The data storedin T may be compared to the data in permanent storage location P(N); ifthe values of the data stored in T differ from the values of the datastored in P(N) by more than a user specified amount, then the data in Tis preferably copied into a new permanent storage location, P(N+1). As aresult, there may then be N+1 permanently stored data sets.

Referring now to FIGS. 11A-11B, graphs 1100, 1150 illustrate plots ofresistance values with respect to time for a given tape drive. Thenumber of data points included in the graphs 1100, 1150 was reduced froman initial number of collected data points. Looking specifically to FIG.11A, a clip performance value of 2 ohms was used to compress anoriginally collected 172 data points to the 22 data points included ingraph 1100, thereby resulting in a 88.4% reduction. Similarly, a clipperformance value of 4 ohms was used in the embodiment corresponding toFIG. 11B, thereby compressing the originally collected 172 data pointsto the 10 data points included in graph 1150, thereby resulting in a94.2% reduction.

FIGS. 12A-12B include graphs 1200, 1250 which illustrate plots of SNRwith respect to time for a given tape drive. Again, the number of datapoints included in the graphs 1200, 1250 was reduced from an initialnumber of collected data points. Looking specifically to FIG. 12A, aclip performance value of 1 was used to compress an originally collected1539 data points to the 63 data points included in graph 1200, therebyresulting in a 95.9% reduction. Similarly, a clip performance value of 2was used in the embodiment corresponding to FIG. 12B, therebycompressing the originally collected 1539 data points to the 38 datapoints included in graph 1250, thereby resulting in a 97.5% reduction.

Looking now to FIGS. 13A-13B, graphs 1300, 1350 illustrate plots of C1BER measurements with respect to time for a given tape drive. Again, thenumber of data points included in the graphs 1300, 1350 was reduced froman initial number of collected data points. Looking specifically to FIG.13A, a clip performance value of 0.5 was used to compress an originallycollected 688 data points to the 69 data points included in graph 1300,thereby resulting in a 89.7% reduction. Similarly, a clip performancevalue of 1 was used in the embodiment corresponding to FIG. 13B, therebycompressing the originally collected 688 data points to the 36 datapoints included in graph 1350, thereby resulting in a 94.6% reduction.

Similarly, FIGS. 14A-14B include graphs 1400, 1450 which illustrateplots of C1 BER measurements with respect to time for two differenttracks of a given tape drive. Here the number of data points included inthe graphs 1400, 1450 was reduced from an initial number of collecteddata points by implementing the same clip performance values to the datacollected to each of the different tracks. Looking specifically to FIG.14A, the originally collected 368 data points were compressed to the 13data points included in graph 1400, thereby resulting in a 96.5%reduction for track 16. Similarly, in FIG. 14B the originally collected368 data points were compressed to the 33 data points included in graph1450, thereby resulting in a 91.0% reduction for track 1. Here, thelarger number of data points resulting for track 1 compared with thedata points resulting for track 16 may result from a larger variabilityin track 1 as opposed to track 16.

Looking now to FIGS. 15A-15B, graphs 1500, 1550 depict plots of C2 BERmeasurements with respect to time for a given tape head. Lookingspecifically to FIG. 15A, a clip performance value of 0.5 and a dFClipvalue of 0.5 for log 10(C2BER) were implemented to compress anoriginally collected 368 data points to the 169 data points included ingraph 1500, thereby resulting in a 54% reduction. Similarly, a clipperformance value of 1 and a dFClip value of 0.5 for log 10(C2BER) wereused in the embodiment corresponding to FIG. 15B, thereby compressingthe originally collected 368 data points to the 48 data points includedin graph 1550, thereby resulting in a 87% reduction.

However, it should be noted that although graph 1550 of FIG. 15Bincludes significantly fewer points than graph 1500 of FIG. 15A, theadded data compression in graph 1550 caused significant data transitionsto be lost (e.g., cut out). According to one approach, additionalstatistical data, e.g., such as the range, average, standard deviation,etc. for each point, may be collected and preferably used to recoversome of the lost data information. For example, if the data of graph1550 is used with the average, range and/or standard deviation betweenpoints being collected, the 48 points becomes 3×48=144, thereby raisingthe amount of data up to the same level as that included in graph 1500.Although this process may increase the amount of data included by about100% for each additional point, it may be desirable in view of therecaptured performance data, e.g., in terms of problem analysis.

FIGS. 16A-16B include graphs 1600, 1650 which depict C2 BER measurementswith respect to time for a given tape head. Specifically, graphs 1600,1650 include data corresponding to re-write measurements for forward andreverse modules, respectively. Here the number of data points includedin the graphs 1600, 1650 was reduced from an initial number of collecteddata points by implementing the same clip performance value of 0.3 anddFClip value of 0.5 for log 10(C2BER) to the data collected in both theforward and reverse modules. Looking specifically to FIG. 16A, theoriginally collected 368 data points were compressed to the 101 datapoints included in graph 1600, thereby resulting in a 73% reduction forthe forward module. Similarly, in FIG. 16B the originally collected 368data points were compressed to the 16 data points included in graph1650, thereby resulting in a 95.7% reduction for the reverse module.

As mentioned above, tape drives may include multiple data read and/orwrite channels. In such tape drives, the error correction codes may berobust and may accordingly tolerate multiple poorly performingparameters before the tape drive itself fails (e.g., is inoperable). Forexample, for a 32 channel tape drive, the probability of the drivesurviving with only one poorly performing track may be close to 100%,but the survival probability decreases as the number of poorlyperforming tracks increases. Accordingly, the probability of failureincreases as the number of poorly performing tracks increases.Therefore, a metric which uses the rate of accumulation of poorperforming tracks may be used to predict future failure conditions asdescribed herein. According to different approaches, the metrics usedmay include resistance, SNRa, Amplitude, etc. In other approaches, anincreased number of read and/or write attempts, error rates (e.g., BER),etc., may be used to predict a future failure condition.

A function which represents the probability of failure may depend on thenumber of failing tracks “N_(poor)”. Moreover, the function may furtherbe represented in terms of the number of poorly performing tracks (e.g.,a SNR value below SNRmin) versus a use parameter “x”, e.g., representedby F(N_(poor)(x)). As described above, examples of a use parameter x maybe time since the drive was built, the number of tapes written to, thenumber of full-file-passes on tape, the total amount of data written,etc. Values for the parameters N_(poor) and x are measured andcollected, e.g., for use with different performance data, such as BER,SNR, resistance, resolution, etc.

N_(poor)(x) may be fit to a function, whereN_(poor)(x)=(1−exp((t/τ_(d))^(β))), such that τ and β are fittingparameters. The function may preferably be used to extrapolate aprojected time for failure. For example, Table 2 below presents a listof failure probability values for F relative to a corresponding SNR.According to the present example, the tape drive may preferably report a50% failure rate which corresponds to a N_(poor) value of 4. Thus, thedata corresponding to values of 1, 2 and/or 3 for N_(poor) may be usedto project a measure of use, e.g., the amount of time, until a value of4 for N_(poor) is reached. The table may be generated using fieldfailures and updated as more data is collected.

TABLE 2 N_(poor) (#) 1 2 3 4 5 6 7 8 9 F (%) 10 25 40 50 60 80 90 95 100

According to yet another example, some magnetic tape heads may includetwo write transducers for each read transducer. Accordingly, one writetransducer may be used to write data in a first direction, while thesecond transducer may be used to write data in a second directionopposite the first direction. Therefore, it may be concluded that one ofthe write transducers is performing poorly (e.g., is damaged) inresponse to determining that the read-back amplitude and/or SNR is in adesirable range while reading data written by the first write transducerin the first direction, while the read-back amplitude and/or SNR is inan undesirable range while reading data written by the second writetransducer in the second direction. An indication of the poorlyperforming write transducer is preferably stored, e.g., the drive codemay record a fault symptom code associated with the particular writer. Asimilar approach can be used in the case of two readers per writer, thatif one reader functions properly while the second reader performspoorly, then the problem is with the poor performing reader and not thewriter.

It follows that various embodiments described herein may be able toperform problem analysis to predict future failure conditions andpreferably issue warnings to avoid such failure conditions. Bycollecting and analyzing stored performance information concerning tapehead and/or tape drive quality, efficiency of tape drive operation as awhole may be improved.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), a ROM, anerasable programmable read-only memory (EPROM or Flash memory), a staticrandom access memory (SRAM), a portable compact disc read-only memory(CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk,a mechanically encoded device such as punch-cards or raised structuresin a groove having instructions recorded thereon, and any suitablecombination of the foregoing. A computer readable storage medium, asused herein, is not to be construed as being transitory signals per se,such as radio waves or other freely propagating electromagnetic waves,electromagnetic waves propagating through a waveguide or othertransmission media (e.g., light pulses passing through a fiber-opticcable), or electrical signals transmitted through a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Moreover, a system according to various embodiments may include aprocessor and logic integrated with and/or executable by the processor,the logic being configured to perform one or more of the process stepsrecited herein. By integrated with, what is meant is that the processorhas logic embedded therewith as hardware logic, such as an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), etc. By executable by the processor, what is meant is that thelogic is hardware logic; software logic such as firmware, part of anoperating system, part of an application program; etc., or somecombination of hardware and software logic that is accessible by theprocessor and configured to cause the processor to perform somefunctionality upon execution by the processor. Software logic may bestored on local and/or remote memory of any memory type, as known in theart. Any processor known in the art may be used, such as a softwareprocessor module and/or a hardware processor such as an ASIC, a FPGA, acentral processing unit (CPU), an integrated circuit (IC), etc.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

The inventive concepts disclosed herein have been presented by way ofexample to illustrate the myriad features thereof in a plurality ofillustrative scenarios, embodiments, and/or implementations. It shouldbe appreciated that the concepts generally disclosed are to beconsidered as modular, and may be implemented in any combination,permutation, or synthesis thereof. In addition, any modification,alteration, or equivalent of the presently disclosed features,functions, and concepts that would be appreciated by a person havingordinary skill in the art upon reading the instant descriptions shouldalso be considered within the scope of this disclosure.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. A computer-implemented method, comprising:collecting performance data corresponding to a tape drive and/or amagnetic tape head, wherein the performance data includes a resistanceof the tape drive and/or magnetic tape head and a resolution of the tapedrive and/or the magnetic tape head; storing the performance data inmemory; and using the data to perform problem analysis, whereinperforming the problem analysis includes: determining a condition of thetape drive and/or the magnetic tape head, wherein the condition isselected from a group consisting of: wear, corrosion, defective leadsand wire bonds.
 2. The computer-implemented method as recited in claim1, wherein performing the problem analysis includes: calculating aneffective stripe height of one or more transducers on the magnetic tapehead and/or an effective magnetic spacing between one or moretransducers on the magnetic tape head and a magnetic tape.
 3. Thecomputer-implemented method as recited in claim 2, comprising:outputting an indication of wear in response to determining that theeffective stripe height has changed and the effective magnetic spacinghas changed for a given one of the transducers; and outputting anindication of accumulation on the magnetic tape head in response todetermining that the effective stripe height has not changed and theeffective magnetic spacing has changed.
 4. The computer-implementedmethod as recited in claim 1, comprising: detecting a change in theresistance of the tape drive and/or magnetic tape head which is largerthan can be ascribed to wear; and determining that corrosion, defectiveleads and/or a wire bond issue are present in response to detecting thechange.
 5. The computer-implemented method as recited in claim 1,wherein performing the problem analysis includes: identifying amechanical bond issue and/or predicting future failure conditions of thetape drive and/or the magnetic tape head.
 6. The computer-implementedmethod as recited in claim 1, wherein performing the problem analysisincludes: tracking changes to the performance data over time;reconstructing when a change in performance of the tape drive and/or themagnetic tape head occurred at a previous point in time; andextrapolating future failure conditions of the tape drive and/or themagnetic tape head from the tracked changes in the performance data. 7.The computer-implemented method as recited in claim 6, comprising:determining a cause of the change in performance of the tape driveand/or the magnetic tape head in response to reconstructing when thechange in performance of the tape drive and/or the magnetic tape headoccurred at the previous point in time.
 8. A computer program productcomprising a computer readable storage medium having programinstructions embodied therewith, the program instructions executable bya controller to cause the controller to: collect, by the controller,performance data corresponding to a tape drive and/or a magnetic tapehead, wherein the performance data includes a resistance of the tapedrive and/or magnetic tape head and a resolution of the tape driveand/or the magnetic tape head; store, by the controller, the performancedata in memory; and use, by the controller, the data to perform problemanalysis, wherein performing the problem analysis includes: determining,by the controller, a cause of an issue of the tape drive and/or themagnetic tape head, wherein the cause of the issue is selected from agroup consisting of: wear, corrosion, defective leads and wire bonds. 9.The computer program product as recited in claim 8, wherein performingthe problem analysis includes: calculating, by the controller, aneffective stripe height of one or more transducers on the magnetic tapehead and/or an effective magnetic spacing between one or moretransducers on the magnetic tape head and a magnetic tape.
 10. Thecomputer program product as recited in claim 9, the program instructionsexecutable by the controller to cause the controller to: output, by thecontroller, an indication of wear in response to determining that theeffective stripe height has changed and the effective magnetic spacinghas changed for a given one of the transducers; and output, by thecontroller, an indication of accumulation on the magnetic tape head inresponse to determining that the effective stripe height has not changedand the effective magnetic spacing has changed.
 11. The computer programproduct as recited in claim 8, the program instructions executable bythe controller to cause the controller to: detect, by the controller, achange in the resistance of the tape drive and/or magnetic tape headwhich is larger than can be ascribed to wear; and determine, by thecontroller, that corrosion, defective leads and/or a wire bond issue arepresent in response to detecting the change.
 12. The computer programproduct as recited in claim 8, wherein performing the problem analysisincludes: identifying, by the controller, a mechanical bond issue and/orpredicting, by the controller, future failure conditions of the tapedrive and/or the magnetic tape head.
 13. The computer program product asrecited in claim 8, wherein performing the problem analysis includes:tracking, by the controller, changes to the performance data over time;reconstructing, by the controller, when a change in performance of thetape drive and/or the magnetic tape head occurred at a previous point intime; and extrapolating, by the controller, future failure conditions ofthe tape drive and/or the magnetic tape head from the tracked changes inthe performance data.
 14. The computer program product as recited inclaim 13, the program instructions executable by the controller to causethe controller to: determine, by the controller, a cause of the changein performance of the tape drive and/or the magnetic tape head inresponse to reconstructing when the change in performance of the tapedrive and/or the magnetic tape head occurred at the previous point intime.
 15. A system, comprising: a processor and logic integrated withand/or executable by the processor, the logic being configured to causethe processor to: collect performance data corresponding to a tape driveand/or a magnetic tape head, wherein the performance data includes aresistance of the tape drive and/or magnetic tape head and a resolutionof the tape drive and/or the magnetic tape head; store the performancedata in memory; and use the data to perform problem analysis, whereinperforming the problem analysis includes: determining a condition of thetape drive and/or the magnetic tape head, wherein the condition isselected from a group consisting of: wear, corrosion, defective leadsand wire bonds.
 16. The system as recited in claim 15, whereinperforming the problem analysis includes: calculating an effectivestripe height of one or more transducers on the magnetic tape headand/or an effective magnetic spacing between one or more transducers onthe magnetic tape head and a magnetic tape.
 17. The system as recited inclaim 16, comprising logic being configured to cause the processor to:output an indication of wear in response to determining that theeffective stripe height has changed and the effective magnetic spacinghas changed for a given one of the transducers; and output an indicationof accumulation on the magnetic tape head in response to determiningthat the effective stripe height has not changed and the effectivemagnetic spacing has changed.
 18. The system as recited in claim 15,comprising logic being configured to cause the processor to: detect achange in the resistance of the tape drive and/or magnetic tape headwhich is larger than can be ascribed to wear; and determine thatcorrosion, defective leads and/or a wire bond issue are present inresponse to detecting the change.
 19. The system as recited in claim 15,wherein performing the problem analysis includes: identifying amechanical bond issue and/or predicting future failure conditions of thetape drive and/or the magnetic tape head.
 20. The system as recited inclaim 15, wherein performing the problem analysis includes: trackingchanges to the performance data over time; reconstructing when a changein performance of the tape drive and/or the magnetic tape head occurredat a previous point in time; extrapolating future failure conditions ofthe tape drive and/or the magnetic tape head from the tracked changes inthe performance data; and determining a cause of the change inperformance of the tape drive and/or the magnetic tape head in responseto reconstructing when the change in performance of the tape driveand/or the magnetic tape head occurred at the previous point in time.